This invention relates to a push-pull amplifier circuit which can be used as the power amplifier for audio equipment or the like.
A fundamental aspect of such an amplifier is a class "A" or class "B" complementary push-pull amplifier circuit. In the class "A" push-pull amplifier, the operations of a pair of output transistors are effected in the active regions at all times and are never shifted into the cut-off regions. Therefore, the class "A" push-pull amplifier is advantageous in that no switching distortion is caused, but it is still disadvantageous in that its thermal loss is increased because of the relatively large biasing current required. Conversely, the class "B" push-pull amplifier is advantageous in that the bias current is smaller to reduce the thermal loss. However, it is also disadvantageous in that switching distortion is caused because a pair of output transistors are operated by alternatively switching their operation states into the active state and the cut-off state.